Legionella pneumophila, which is the causal agent of Legionella infections, has been known to cause Legionnaires' disease or Pontiac fever. Since the bacteria was first isolated in Philadelpia, USA, it has been reported that many isolations of a species of Legionella were made from various patients and environments in all parts of the world, including the USA, and 10 or more species were identified. Legionella pneumophila is one of the pathogens capable of causing pneumonia and it is presumed that 5% of the occurences of pneumonia are due to Legionella pneumophila. Legionella pneumophila grows in air-conditioning cooling towers, water service pipes, drain pipes, etc., and infections are believed to occur in respiratory organs by inhalation of contaminated aerosols. In July, 1984, criticism was caused by the surprising fact that ill-defined symptoms of pneumonia which occurred in patients as well as medical teams at intensive care units of Koryo Hospital in Seoul appeared to be caused by Legionella species.
According to a result of investigation completed in 1985 by the National Health Institute, at least 90% of air-conditioning cooling towers within Seoul were contaminated with Legionella species and 93% of the isolated Legionella were identified as Legionella pneumophila. An additional investigation completed by the National Health Institute in major cities throughout the country, for example Seoul, Pusan, Daejeon, etc., between June and September, 1988 revealed that 83% of the isolated Legionella were classified to Legionella pneumophila serogroup 1.
Macrolide antibiotics, such as erythromycin, and quinolone antibiotics, such as rifampin, are known to be active against Legionella species and have been used for the treatment of the Legionella infections. However, these antibiotics have a wide spectrum of activity against a variety of microbes, in addition to the Legionella species. In this regard, an abuse of such antibiotics for extended periods may not only generate resistance to various microbes but also cause harmful problems such as the collapse of the balance of microbes occurring in a human body.
Additionally, there have been serious problems in that chemical agents for disinfecting air-conditioning cooling towers, which are contamination sources of Legionella species, may result in the contamination of the environment and the corrosion of the air-conditioning device.
Therefore, the development of novel Legionella specific antibiotics which are specifically active against only Legionella species, is needed and thereby may minimize the undesired problems. We have intensively investigated soil microbes over several years for the purpose of developing such antibiotics. Eventually, we succeeded in isolating a species of Streptomyces producing Legionella specific antibiotics and purifying a novel antibiotic specifically active against only Legionella species, which is designated Antibiotic AL072.